Special boring bar



June 16, 1953 D. WHITE 2,641,940

SPECIAL BORING BAR Filed Aug. 9, .949

grime/whom DAN WHITE Patented June 16, i953 UN TED--{STAT S PATENT OFFlCE z,641,94o sPEcIALBoRING Ban 1 I Dan White, Cleveland, Ohio 1 Amiuatmnnughst 9,1949, Serial No. 109,383 v "3 Claims. (01. 7758) .(Granted underTTitle sans; Code (1952),. L

. sec.

- This invention relates generally to boring bars and specifically to a boring bar for cutting deep holes in metal at high speeds.

At present it is impossible to accurately bore deep holes in hard metals with a boring bar due to the chatter of the tool in the cavity and the resultant rough surfaces and errors in the diameter of the bore with possible breakage of the boring bar. It is usually necessary to finish the internal surface of the bore after using a conventional boring bar at high speeds by reaming or otherwise treating said surface to remove chatter marks. Slow speeds of feed and rotation are generally necessary to prevent chatter in boring deep holes or cavities in most metals.

An object of the present invention is to provide a boring bar of such construction that will permit it to be used without chattering at speeds greater, thanis possible with present tools.

Another object of the invention is to provide a boring bar which can be used at any lathespeeds without chattering and consequent roughening of the surface cut.

Another object is to provide a boring bar hav- Other objects and features of the invention will become apparent tothose skilled in the art as the disclosure is made in the following detailed description of a preferred embodiment of the invention as illustrated in the accompanying sheet of drawing in which:

Fig. 1 is a top view partially in section of one embodiment of the invention.

Fig. 2 is a top view partly in section of another embodiment of the invention.

Fig. 3 is an end view of the embodiment shown in Fig. 2.

Fig. 4 is a top view partly in section of still another embodiment of the invention.

Referring in more particular to the drawing, in Fig. 1 is shown a boring bar l0 secured at one end in a tool holder I I such as is used on a lathe, boring machine or. the like. A cutting tool bit I2 is secured in opening [3 in the boring bar it by set screw l 4 in the conventional manner. 'Adjacent the end of-the boring bar [0 which holds the cutting tool bit [2 is cavity 15 formed or drilled therein and filling the cavity I5 is a powdered material It of a composition to be de- I scribed later. The cavity 2 I p i5 is closed by a threaded *plug H engaging the internal threads 18 of the entrance to the cavity G5.

I In Fig. 2 another embodiment of the invention is shown with the cavity i5 drilled in the end of the boring bar 20 and filled with powdered material IS. The cavity I5 is in this embodiment closed by plug 2| welded to the boring bar.

In Fig. 3 the end of the boring bar 20 of Fig. 2 is shown in end view. Fig. 4 shows still another embodiment of-a boring bar 30 having around it near the cutting tool bit 12 an annular collar 3| formed so as to enclose an amount of loose material [6". The collar 3| may be secured to the boring bar 30 by a press fit or by welding, or in any other conventional manner.

Experiments have shown that the cavity H5,

or l5 or the space in the annular collar 3| may be filled to approximately of capacity with a powder made of tungsten, or of tungsten carbide, and that satisfactory results of no appre ciable chatter may be thusly obtained. Other substances may be used without departing from the scope and breath of the invention. Certain no-chatter characteristics may be imparted to a tool by the use of liquid mercury in'the cavity for'some uses, and the cavity may be filled to other limits ofcapacity than the 90%. Likewise, theiinvention may be applied to other cutting tools and may be used on lathe tools generally and on cut-01f tools used on metals which normally present a problem of chatter and spoilage of the finished surface of the metal.

Additional energy absorption means may be,

applied tothe boring bar to increase further its effectivenessas a cutting tool. strip of copper may be inserted in the tool bit opening [3 and partially or completely encircle the bit l2, andthus'cushion it against the bar In. For example, a -inch thick strip having approximately the width of the tool bit l2 and placed under it in the opening 43 prevented chattering of the 1:001.

As a still further aid in reducing the chatter of the tool, the bar Ill may be coated byany suitable means, such as by electrode position or dipping or a combination of both, with a layer of copper and lead, and all or part of the bar may be so coated. For example, the entire bar may be coated with a. .002-inch layer of copper, and that portion of the copper layer on the bar it from the end holding the tool bit I 2 to the center of the bar may be covered with a .004-inch layer of lead. T

Furthermore, the boring bar It may be made from material having high inherent damping A relatively thick 7 properties. From tests, it has been determined that hardened tool steel boring bars will chatter the most whereas a perlitic cast iron boring bar will chatter the least.

The foregoing relates only to preferred embodiments of the invention and numerous modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A tool for metal working comprising a body,

a bore in said body, the axis of said bore being perpendicular to a plane through the center line the surface of the body on one side of the afore-' said plane, at least one half of said bore being on the opposite side of said plane, and a freely movable, non-packing, high density powdered substance partially filling said bore so as to permit the movement of more than half of the powdered substance into the above mentioned half of said bore when the tool is rotated.

2. A tool as set forth in claim 1 wherein the powdered-substance is composed of tungsten.

31A tool as set forth in claim 1 wherein the powdered substance is composed of tungsten carbide.

DAN WHITE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,051,954 Leland Aug. 25, 1936 2,224,386 Guild Dec. 10, 1940 2,375,818 Peters May 15, 1945 2,469,167 Little May 3, 1949 

